A Randomized Comparison of Radiation Therapy Techniques in the Management of Node-Positive Breast Cancer: Primary Outcomes Analysis.
Abstract PURPOSE: Although inverse-planned intensity modulated radiotherapy (IMRT) and deep inspiration breath hold (DIBH) may allow for more conformal dose distributions, it is unknown whether using these technologies reduces cardiac or pulmonary toxicity of breast radiotherapy. METHODS AND MATERIALS: A randomized controlled trial compared IMRT-DIBH versus standard, free-breathing, forward-planned, three-dimensional conformal radiotherapy in patients with left-sided, node-positive breast cancer in whom the internal mammary nodal region was targeted. Endpoints included dosimetric parameters and changes in pul...
Source: Physics in Medicine and Biology - July 19, 2018 Category: Physics Authors: Jagsi R, Griffith KA, Moran JM, Ficaro E, Marsh R, Dess RT, Chung E, Liss AL, Hayman JA, Mayo CS, Flaherty K, Corbett J, Pierce L Tags: Int J Radiat Oncol Biol Phys Source Type: research

4D dose calculation for PBS proton therapy of pancreatic cancer using repeated 4DMRI datasets.
In this study, we aim to show the feasibility of 4D treatment planning for pencil beam scanning (PBS) proton therapy of pancreatic cancer, based on repeated 4DMRI datasets and 4D dose calculations (4DDC). To investigate the dosimetric impacts of organ motion, deformation vector fields were extracted from 4DMRI, which were then used to warp a static CT of a patient, so as to generate synthetic 4DCT (4DCT-MRI). The results from 4DDC show pronounced interplay effects in the CTV with dose homogeneity d5/d95 and dose coverage v95 being 1.14 and 91%, respectively, after a single fraction of the treatment. An averaging effec...
Source: Physics in Medicine and Biology - July 18, 2018 Category: Physics Authors: Dolde K, Naumann P, Dávid C, Gnirs R, Kachelrieß M, Lomax AJ, Saito N, Weber DC, Pfaffenberger A, Zhang Y Tags: Phys Med Biol Source Type: research

Relative Patlak plot for dynamic PET parametric imaging without the need for early-time input function.
Abstract The Patlak graphical method is widely used in parametric imaging for modeling irreversible radiotracer kinetics in dynamic PET. The net influx rate of radiotracer can be determined from the slope of the Patlak plot. The implementation of the standard Patlak method requires the knowledge of full-time input function from the injection time until the scan end time, which presents a challenge for use in the clinic. This paper proposes a new relative Patlak plot method that does not require early-time input function and therefore can be more efficient for parametric imaging. Theoretical analysis proves that th...
Source: Physics in Medicine and Biology - July 18, 2018 Category: Physics Authors: Zuo Y, Qi J, Wang G Tags: Phys Med Biol Source Type: research

Prediction of chemotherapy response in ovarian cancer patients using a new clustered quantitative image marker.
In conclusion, this study demonstrates the potential of our proposed new quantitative image marker fused with the features computed from both spatial and frequency domain for a reliable prediction of tumor response to postsurgical chemotherapy. PMID: 30010611 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 16, 2018 Category: Physics Authors: Zargari A, Du Y, Heidari M, Thai T, Gunderson C, Moore K, Mannel R, Liu H, Zheng B, Qiu Y Tags: Phys Med Biol Source Type: research

Validating a Monte Carlo approach to absolute dose quality assurance for proton pencil beam scanning.
In conclusion, an automated, easy-to-use Monte Carlo calculation system has been set up. This system reproduced patient specific QA results over a wide range of cases, showing that the time consuming measurements could be reduced or even replaced using Monte Carlo simulations without jeopardizing treatment quality. PMID: 30010613 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 16, 2018 Category: Physics Authors: Winterhalter C, Fura E, Tian Y, Aitkenhead AH, Bolsi A, Dieterle M, Fredh A, Meier G, Oxley D, Siewert D, Weber DC, Lomax AJ, Safai S Tags: Phys Med Biol Source Type: research

Iterative Spectral CT Reconstruction Based on Low Rank and Average-Image-Incorporated BM3D.
Abstract In a photon counting detector integrated spectral CT scanner, the received photons are counted in several energy channels to generate the corresponding projections. Since the projection in each energy channel is generated using part of the received photons, the reconstructed channel image suffers from severe noises. Therefore, image reconstruction in spectral CT is considered as a big challenge. Because the inter-channel images are all from the same object but in different energy bins, there exists a strong correlation among these images. Moreover, it is suggested that there are similarities among various...
Source: Physics in Medicine and Biology - July 13, 2018 Category: Physics Authors: Salehjahromi M, Zhang Y, Yu H Tags: Phys Med Biol Source Type: research

A small number of objective function weight vectors is sufficient for automated treatment planning in prostate cancer.
Abstract Current practice for treatment planning optimization can be both inefficient and time consuming. In this paper, we propose a automated planning methodology that aims to combine both explorative and prescriptive approaches for improving the efficiency and the quality of the treatment planning process. Given a treatment plan, our explorative approach explores trade-offs between different objectives and finds an acceptable region for objective function weights via inverse optimization. Intuitively, the shape and size of these regions describe how "sensitive" a patient is to perturbations in objecti...
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Goli A, Boutilier JJ, Craig T, Sharpe MB, Chan TCY Tags: Phys Med Biol Source Type: research

Optimized I-values for the use with the Bragg additivity rule and their impact on proton stopping power and range uncertainty.
Conclusion: We propose a set of elemental I-values well suited for human tissues in combination with the BAR. Our model establishes uncertainties on elemental I-values and the BAR, enabling to quantify uncertainties on tissue I-values, RSP as well as particle range. This work is particularly relevant for Monte Carlo simulations where the interaction probabilities are reconstructed from elemental compositions. PMID: 29999493 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Bär E, Andreo P, Lalonde A, Royle GJ, Bouchard H Tags: Phys Med Biol Source Type: research

Suggested reference values for regional blood volumes in children and adolescents.
Abstract Estimates of regional blood volumes (BVs) in humans are needed in dosimetric models of radionuclides and radiopharmaceuticals that decay in the circulation to a significant extent. These values are also needed to refine models of tissue elemental composition in computational human phantoms of both patients and exposed members of the general public. The International Commission on Radiological Protection (ICRP) in its Publication 89 provides reference values for total blood content in the full series of their reference individuals, to include the male and female newborn, 1-year-old, 5-year-old, 10-year-old...
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Wayson MB, Leggett RW, Jokisch DW, Lee C, Schwarz B, Godwin W, Bolch WE Tags: Phys Med Biol Source Type: research

LEFMIS: Locally-oriented Evaluation Framework for Medical Image Segmentation algorithms.
Conclusion: The article shows the greater usefulness and flexibility of the proposed framework in comparison to the state-of-the-art methods. The exemplary usage of the LEFMIS with or without inter-/intra-observer variability is also presented. PMID: 29999495 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Skalski A, Jakubowski J, Drewniak T Tags: Phys Med Biol Source Type: research

Flexible optically stimulated luminescence band for 1-D < i > in vivo < /i > radiation dosimetry.
Flexible optically stimulated luminescence band for 1-D in vivo radiation dosimetry. Phys Med Biol. 2018 Jul 12;: Authors: Kim TJ, Jung K, Fahimian BP, Pratx G Abstract In vivo dosimetry helps ensure the accuracy of radiation treatments. However, standard techniques are only capable of point sampling, making it difficult to accurately measure dose variation along curved surfaces in a continuous manner. The purpose of this work is to introduce a flexible dosimeter band and validate its performance using pre-clinical and clinical X-ray sources. Dosimeter bands were fabricated by uniformly mixing BaFBr:E...
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Kim TJ, Jung K, Fahimian BP, Pratx G Tags: Phys Med Biol Source Type: research

Suitability of low density materials for 3D printing of physical breast phantoms.
Abstract Breast physical phantoms are a basic tool for the assessment and verification of performance standards in daily clinical practice of x-ray breast imaging modalities. They are also invaluable in testing and evaluation of new x-ray breast modalities to be potentially established, e.g. breast computed tomography, dual-energy breast CT and phase-contrast mammography and tomography. Nowadays, there is a lack or there are only a limited number of breast physical phantoms available for this purpose. The aim of this study is to explore a range of 3D printing materials such as resins, PLA, ABS, Nylon etc., to...
Source: Physics in Medicine and Biology - July 12, 2018 Category: Physics Authors: Ivanov D, Bliznakova K, Buliev I, Popov P, Mettivier G, Russo P, Di Lillo F, Sarno A, Vignero J, Bosmans H, Bravin A, Bliznakov Z Tags: Phys Med Biol Source Type: research

Estimation of the NEMA characteristics of the J-PET tomograph using the GATE package.
a M, Pawlik-Niedźwiecka M, Raj J, Rakoczy K, Rudy Z, Sharma S, Shivani S, Silarski M, Skurzok M, Zgardzińska BK, Zielinski M, Moskal P Abstract The novel whole-body PET system based on plastic scintillators is developed by the J-PET Collaboration. It consists of plastic scintillator strips arranged axially in the form of a cylinder, opening perspective for the cost-effective construction of the total-body PET. In order to determine properties of the scanner prototype and optimize its geometry, advanced computer simulations using the GATE software were performed. The spatial resolution, the sensitivity...
Source: Physics in Medicine and Biology - July 11, 2018 Category: Physics Authors: Kowalski P, Wiślicki W, Shopa R, Raczyński L, Klimaszewski K, Curceanu C, Czerwiński E, Dulski K, Gajos A, Gorgol M, Sharma NG, Hiesmayr BC, Jasińska B, Kapłon Ł, Kamińska D, Korcyl G, Kozik T, Krzemień W, Kubicz E, Mohammed M, Niedzwiecki S, Pał Tags: Phys Med Biol Source Type: research

Transesophageal 2D ultrasound to 3D computed tomography registration for the guidance of a cardiac arrhythmia therapy.
er JL Abstract The work aims at developing a new image-processing method to improve the guidance of transesophageal HIFU atrial fibrillation therapy. Our proposal is a novel registration approach that aligns intraoperative 2D ultrasound with preoperative 3D-CT information. This approach takes advantage of the anatomical constraints imposed at the transesophageal HIFU probe to simplify the registration process. Our proposed method has been evaluated on a physical phantom and on real clinical data. . PMID: 29992909 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 11, 2018 Category: Physics Authors: Sandoval Z, Castro M, Alirezaie J, Bessière F, Lafon C, Dillenseger JL Tags: Phys Med Biol Source Type: research

Sub-3 millimeter, near-200 picosecond TOF/DOI-PET imaging with monolithic scintillator detectors in a 70 cm diameter tomographic setup.
Abstract Recently, a monolithic scintillator detector for time-of-flight (TOF) / depth-of-interaction (DOI) positron emission tomography (PET) was developed. It has a detector spatial resolution of ~1.7 mm full-width-at-half-maximum (FWHM), a coincidence resolving time (CRT) of ~215 ps FWHM, and ~4.7 mm FWHM DOI resolution. Here, we demonstrate, for the first time, the imaging performance of this detector in a 70 cm diameter PET geometry. We built a tomographic setup representative of a whole-body clinical scanner, comprising two coaxially rotating arms, each carrying a detector module, and a central, rotating pha...
Source: Physics in Medicine and Biology - July 11, 2018 Category: Physics Authors: Borghi G, Tabacchini V, Bakker R, Schaart DR Tags: Phys Med Biol Source Type: research

Characterization of imaging latency for real-time MRI-guided radiotherapy.
Abstract Hybrid MR-Linac systems can use fast dynamic MR sequences for tumor tracking and adapt the radiation treatment in real-time. For this the imaging latency must be as short as possible. This work describes how different acquisition parameters influence this latency. First, the latency was measured for Cartesian readouts with phase encode orderings linear, reverse-linear, and high-low. Second, the latency was measured for radial readouts with linear and golden angle profile orderings. To reduce the latency, a spatio-temporal (k-t) filter that suppresses the k-space center of ea...
Source: Physics in Medicine and Biology - July 11, 2018 Category: Physics Authors: Borman PTS, Tijssen RHN, Bos C, Moonen CTW, Raaymakers BW, Glitzner M Tags: Phys Med Biol Source Type: research

Small airway segmentation in thoracic computed tomography scans: a machine learning approach.
Abstract Small airway obstruction is a main cause for Chronic Obstructive Pulmonary Disease (COPD). We propose a novel method based on machine learning to extract the airway system from a thoracic computed tomography (CT) scan. The emphasis of the proposed method is on including the smallest airways that are still visible on CT. We used an optimized sampling procedure to extract airway and non-airway voxel samples from a large set of scans for which a semi-automatically constructed reference standard was available. We created a set of features which represent tubular and texture properties that are characteristic ...
Source: Physics in Medicine and Biology - July 11, 2018 Category: Physics Authors: Bian Z, Charbonnier JP, Liu J, Zhao D, Lynch DA, vanGinneken B Tags: Phys Med Biol Source Type: research

Toward adaptive radiotherapy for lung patients: Feasibility study on deforming planning CT to CBCT to assess the impact of anatomical changes on dosimetry.
Conclusion: DIR is a valuable clinical tool for dose recalculation in adaptive radiotherapy protocols for lung cancer patients. . PMID: 29978832 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 6, 2018 Category: Physics Authors: Cole AJ, Veiga C, Johnson U, D'Souza D, Lalli N, McClelland JR Tags: Phys Med Biol Source Type: research

Independent application of an analytical model for secondary neutron equivalent dose produced in a passive-scattering proton therapy treatment unit.
Conclusion: We found that the previously-published analytical model, combined with adjustment factors to enhance its clinical applicability, predicted &lt;i&gt;H&lt;sub&gt;T&lt;/sub&gt;&lt;/i&gt;/&lt;i&gt;D&lt;sub&gt;Rx&lt;/sub&gt;&lt;/i&gt; in out-of-field organs and tissues at risk for subsequent malignant neoplasms with acceptable accuracy. This independent application demonstrated that the analytical model may be useful broadly for clinicians and researchers to calculate equivalent dose from neutrons produced externally to the patient in passive-scattering...
Source: Physics in Medicine and Biology - July 6, 2018 Category: Physics Authors: Gallagher KJ, Taddei PJ Tags: Phys Med Biol Source Type: research

Burst and continuous high frequency irreversible electroporation protocols evaluated in a 3D tumor model.
Abstract High frequency irreversible electroporation (H-FIRE) is an emerging cancer therapy which uses bursts of alternating polarity pulses to target and destroy the membranes of cells within a predictable volume. Typically, 2 µs pulses are rapidly repeated 24-50 times to create a 48-100 µs long energy burst. Bursts are repeated 100×  at 1 Hz, resulting in an integrated energized time of 0.01 s per treatment. A 3D in vitro tumor model was used to investigate H-FIRE parameters in search of optimal energy timing protocols. Monopolar IRE treatments (100  ×&t...
Source: Physics in Medicine and Biology - July 6, 2018 Category: Physics Authors: Sano MB, Fesmire CC, DeWitt MR, Xing L Tags: Phys Med Biol Source Type: research

Polymer gel dosimetry by Nuclear Overhauser Enhancement (NOE) magnetic resonance imaging.
Abstract The response to radiation of polymer gel dosimeters has previously been measured by magnetic resonance imaging (MRI) in terms of changes in the water transverse relaxation rate (R&lt;sub&gt;2w&lt;/sub&gt;) or magnetization transfer (MT) parameters. Here we report a new MRI approach, based on detecting nuclear Overhauser enhancement (NOE) mediated saturation transfer effects, which can also be used to detect radiation and measure dose distributions in MAGIC-f (Methacrylic and Ascorbic Acid and Gelatin Initiated by Copper Solution with formaldehyde) polymer gels. Results show that the NOE ef...
Source: Physics in Medicine and Biology - July 6, 2018 Category: Physics Authors: Quevedo A, Luo G, Galhardo E, Price M, Nicolucci P, Gore JC, Zu Z Tags: Phys Med Biol Source Type: research

Dynamic < sup > 18 < /sup > F-FLT PET imaging of spatiotemporal changes in tumor cell proliferation and vasculature reveals the mechanistic actions of anti-angiogenic therapy.
Conclusions: Imaging with dynamic 18F-FLT PET revealed new insights relating to the interplay of vascular and proliferative pharmacodynamics of axitinib therapy, facilitating a greater understanding of the mechanistic actions of VEGFR-TKIs. Increases in tumor vasculature and cell proliferation during VEGFR-TKI treatment breaks, suggests this period is an optimal time to schedule synergistic chemotherapy and warrants further investigation. . PMID: 29978839 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 6, 2018 Category: Physics Authors: Scarpelli M, Simoncic U, Perlman S, Liu G, Jeraj R Tags: Phys Med Biol Source Type: research

Impact of new ICRU Report 90 recommendations on calculated correction factors for reference dosimetry.
This study indicates that the impact of the new ICRU recommendation is within 0.35%. The determined deviations should be taken into account, when widely published Monte Carlo calculated values are examined. . PMID: 29974869 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 5, 2018 Category: Physics Authors: Czarnecki D, Poppe B, Zink K Tags: Phys Med Biol Source Type: research

Modeling and comparison of alternative approaches for sector duration optimization in a dedicated radiosurgery system.
Abstract Stereotactic radiosurgery (SRS) is an effective technique to treat brain metastasis for which several inverse planning methods may be appropriate. We compare three different models for segment duration optimization in SRS using Leksell Gamma Knife{\textregistered} Icon{\texttrademark} (Elekta, Stockholm, Sweden). We investigate (1) a linear programming approach, (2) a piecewise quadratic penalty approach, and (3) an unconstrained convex moment-based penalty approach. The performance of these approaches is assessed using anonymized data from 14 previously treated cases. The treatment plans obtained via opt...
Source: Physics in Medicine and Biology - July 4, 2018 Category: Physics Authors: Cevik M, Shirvani Ghomi P, Aleman DM, Lee Y, Berdyshev A, Nordstrom H, Riad S, Sahgal A, Ruschin M Tags: Phys Med Biol Source Type: research

A comparative study of physical image quality in digital and synthetic mammography from commercially available mammography systems.
We present a comparison between full field digital mammography and synthetic mammography, performed on several mammography systems from four different manufacturers. The analysis is carried out on both the digital and synthetic images of two commercially available mammography phantoms, and focuses on a set of objective metrics that encode the geometrical appearance of imaging features of diagnostic interest. In particular, we measured sizes and contrasts of several clusters of microcalcification specks, shapes and contrasts of circular masses, and the power spectrum of background regions mimicking the heterogeneous texture...
Source: Physics in Medicine and Biology - July 4, 2018 Category: Physics Authors: Baldelli P, Bertolini M, Contillo A, Della Gala G, Golinelli P, Pagan L, Rivetti S, Taibi A Tags: Phys Med Biol Source Type: research

Anatomically plausible models and quality assurance criteria for online mono- and multi-modal medical image registration.
Abstract Medical imaging is currently employed in the diagnosis, planning, delivery and response monitoring of cancer treatments. Due to physiological motion and/or treatment response, the shape and location of the pathology and organs-at-risk may change over time. Establishing their location within the acquired images is therefore paramount for an accurate treatment delivery and monitoring. A feasible solution for tracking anatomical changes during an image-guided cancer treatment is provided by image registration algorithms. Such methods are, however, often built upon elements originating from the computer ...
Source: Physics in Medicine and Biology - July 4, 2018 Category: Physics Authors: Zachiu C, Denis de Senneville B, Moonen CTW, Raaymakers BW, Ries MG Tags: Phys Med Biol Source Type: research

Enhanced reconstruction algorithm for moir é artifact suppression in Talbot-Lau x-ray imaging.
In conclusion, the proposed reconstruction algorithm facilitates the use of TLXI in clinical practice and allows the exploitation of the method's full diagnostic potential in future medical applications. PMID: 29968576 [PubMed - in process] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 3, 2018 Category: Physics Authors: Hauke C, Anton G, Hellbach K, Leghissa M, Meinel FG, Mertelmeier T, Michel T, Radicke M, Sutter SM, Weber T, Ritschl L Tags: Phys Med Biol Source Type: research

Scalp sensor for simultaneous acoustic emission detection and electroencephalography during transcranial ultrasound.
This study investigates the feasibility of using a novel scalp senor for acquiring concurrent AED and EEG during clinical transcranial ultrasound. A piezoelectric disk is embedded in plastic cup EEG electrode to form the sensor. The sensor is coupled to the head via an adhesive/conductive gel-dot. Components of the sensor prototype are tested for AED and EEG signal quality in a bench top investigation with a functional ex vivo skull phantom. PMID: 29968579 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 3, 2018 Category: Physics Authors: Brinker ST, Crake C, Ives JR, Bubrick EJ, McDannold NJ Tags: Phys Med Biol Source Type: research

Calculation of water equivalent ratios (WER) for various materials at proton energies ranging 10-500 MeV using MCNP, FLUKA, and GEANT4 Monte Carlo codes.
Abstract Dosimetry of proton beams is generally evaluated in liquid water, or alternatively in solid phantoms via water equivalent ratios (WER). WER is defined as the ratio of proton range in liquid water to that in a phantom of certain material. Presently, WER is not available in the literature neither for a wide range of energies nor for variety of relevant materials. Thus, the goal of this study is to provide such data through Monte Carlo simulations. WER is calculated for 10-500 MeV energies for compact bone, adipose tissue, polymethyl methacrylate (PMMA), PTFE (teflon), graphite (C), aluminum (Al), copper (Cu...
Source: Physics in Medicine and Biology - July 3, 2018 Category: Physics Authors: Safigholi H, Song WY Tags: Phys Med Biol Source Type: research

Unsupervised classification of tissues composition for Monte Carlo dose calculation.
In conclusion, k-means clustering successfully reduces the variety of materials needed for accurate MC dose calculation. Based on the performance of four distance measures, we conclude that k-means clustering using the Chi-Squared distance introduces the smallest errors on dose distribution.The method is shown to yield similar or improved accuracy on key physical parameters compared to supervised classification. PMID: 29962371 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - July 2, 2018 Category: Physics Authors: Lalonde A, Remy C, Simard M, Bouchard H Tags: Phys Med Biol Source Type: research

Ki-67 Remains Solely a Prognostic Biomarker in Localized Prostate Cancer.
PMID: 29893267 [PubMed - in process] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 14, 2018 Category: Physics Authors: Spratt DE Tags: Int J Radiat Oncol Biol Phys Source Type: research

Mentorship Experiences of Early-Career Academic Radiation Oncologists in North America.
CONCLUSIONS: These findings suggest a need for academic radiation oncology departments to facilitate mentorship of all junior faculty through deliberate, structured programs, with training of mentors and mentees alike. It is heartening that substantial rates of sponsorship and peer-mentorship use were reported, which may serve as the grounding for further initiatives. PMID: 29893281 [PubMed - in process] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 14, 2018 Category: Physics Authors: Lalani N, Griffith KA, Jones RD, Spratt DE, Croke J, Jagsi R Tags: Int J Radiat Oncol Biol Phys Source Type: research

Evaluation of MRI RF electromagnetic field induced heating near leads of cochlear implants.
Abstract A typical cochlear implant system under Magnetic Resonance Imaging (MRI) procedures may couple with the radio frequency (RF) electromagnetic field (EMF) and results in an intensified electric field at the lead tip. As a result, the RF energy deposited in human tissues around the lead tip may induce heating and cause tissue damage concerns. The purpose of this work is to evaluate the RF-EMF-induced heating for cochlear implant system in 1.5T MRI coil and highlight the factors that have significant effects on the heating. The potential factors involved in the RF-EMF-induced heating including the lead type, ...
Source: Physics in Medicine and Biology - June 12, 2018 Category: Physics Authors: Zeng Q, Wang Q, Zheng JJ, Kainz W, Chen J Tags: Phys Med Biol Source Type: research

A projection image database to investigate factors affecting image quality in weight-based dosing: application to pediatric renal SPECT.
Abstract Please see abstract in the final version of the manuscript. PMID: 29893291 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 12, 2018 Category: Physics Authors: Li Y, O'Reilly SE, Plyku D, Treves ST, Du Y, Fahey FH, Cao X, Jha AK, Sgouros G, Bolch WE, Frey EC Tags: Phys Med Biol Source Type: research

Particle-beam-dependent optimization for Monte Carlo simulation in hadrontherapy using tetrahedral geometries.
In this study, the experiments carried out on a multi-layer computational phantom, and a thorax geometry, show that by applying our method on a coarse mesh, we offer a better dose distribution inside the tumor compared to other density mapping methods, in the same level of detail. This is due to the reduction of the water equivalent path length error from 9.65 $mm$ to 0.62 $mm$ in the case the multi-layer phantom, and from 2.42 $mm$ to 0.48 $mm$ for the thorax geometry. Moreover, a similar dose coverage is obtained with refined tetrahedral meshes. As a consequence of the reduction of the number of tetrahedrons, computation...
Source: Physics in Medicine and Biology - June 12, 2018 Category: Physics Authors: Touileb Y, Ladjal H, Beuve M, Shariat B Tags: Phys Med Biol Source Type: research

Improved sensitivity and limit-of-detection using a receive-only coil in magnetic particle imaging.
We present characterization measurements conducted with the prototype Rx-coil installed in a preclinical MPI scanner. The gradiometric design of the Rx-coil attenuates the unwanted signal contributions arising from the excitation field, leading to a 17 dB lower background level compared to the conventional dual-purpose coil (TxRx-coil), which is crucial for detecting low amounts of MNP. Network analyzer measurements of the frequency-dependent coil sensitivity, as well as spectral analysis of recorded MPI data demonstrate an overall increase of the coil sensitivity of about +12 dB for the Rx-coil. Comparisons of the sensiti...
Source: Physics in Medicine and Biology - June 11, 2018 Category: Physics Authors: Paysen H, Wells J, Kosch O, Steinhoff U, Franke J, Trahms L, Schaeffter T, Wiekhorst F Tags: Phys Med Biol Source Type: research

Variations of quantitative perfusion measurement on dynamic contrast enhanced CT for colorectal cancer: implication of standardized image protocol.
In conclusion, the perfusion measurement is indeed model dependent and image acquisition/processing technique dependent. The radiation dose of DCE-CT was on average 1.5-2 times of an abdomen/pelvic CT, which is not insubstantial. To take the DCE-CT forward as a biomarker in oncology, prospective studies should be carefully designed with the optimal image acquisition and analysis technique. PMID: 29889046 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 11, 2018 Category: Physics Authors: Niu T, Yang P, Sun X, Mao T, Xu L, Yue NJ, Kuang Y, Shi L, Nie K Tags: Phys Med Biol Source Type: research

Geometric and dosimetric evaluations of atlas-based segmentation methods of MR images in the head and neck region.
Abstract Owing to its excellent soft-tissue contrast, magnetic resonance (MR) imaging has found an increased application in radiation therapy (RT). Harnessing these properties for treatment planning, automated segmentation methods can alleviate the manual workload burden to the clinical workflow. We investigated atlas-based segmentation methods of organs at risk (OARs) in the head and neck (H&N) region: one approach selecting the most similar atlas from a library of segmented images and two multi-atlas approaches. The latter were based on weighted majority voting and an iterative atlas-fusion appro...
Source: Physics in Medicine and Biology - June 8, 2018 Category: Physics Authors: Kieselmann JP, Kamerling CP, Burgos N, Menten MJ, Fuller CD, Nill S, Cardoso MJ, Oelfke U Tags: Phys Med Biol Source Type: research

Phantom evaluations of nonlinear inversion MR elastography.
This study evaluated non-linear inversion MRE (NLI-MRE) based on viscoelastic governing equations to determine its sensitivity to small, low contrast inclusions and interface changes in shear storage modulus and damping ratio. Reconstruction parameters identical to those used in recent in vivo MRE studies of mechanical property variations in small brain structures were applied. NLI-MRE was evaluated on four phantoms with contrast in stiffness and damping ratio. Image contrast to noise ratio was assessed as a function of inclusion diameter and property contrast, and edge and line spread functions were calculated as measures...
Source: Physics in Medicine and Biology - June 7, 2018 Category: Physics Authors: Solamen LM, McGarry MDJ, Tan L, Weaver JB, Paulsen KD Tags: Phys Med Biol Source Type: research

Mean glandular dose to patients from stereotactic breast biopsy procedures.
yoa J Abstract The aim of this work is to study the radiation doses delivered to a group of patients that underwent a stereotactic breast biopsy (SBB) procedure. Mean glandular doses (MGD) were estimated from the air-kerma measured at the breast surface entrance multiplying by specific conversion coefficients (DgN) that were estimated using Monte Carlo simulations. DgN were calculated for the 0º and ±15º projections used in SBB and for the particular beam quality. Data on 61 patients were collected showing that a typical SBB procedure is composed by 10 images. MGD was on average (4 ± 2) mGy...
Source: Physics in Medicine and Biology - June 7, 2018 Category: Physics Authors: Paixão L, Chevalier M, Hurtado-Romero AE, Garayoa J Tags: Phys Med Biol Source Type: research

An automated planning strategy for near real-time adaptive proton therapy in prostate cancer.
This study's purpose is to develop and evaluate an automated method for adaptation of IMPT plans in near real-time to the anatomy of the day. We developed an automated treatment plan adaptation method using (1) a restoration of spot positions (Bragg peaks) by adapting the energies to the new water equivalent path lengths; and (2) a spot addition to fully cover the target of the day, followed by a fast Reference Point Method optimization of the spot weights resulting in a Pareto optimal plan for the daily anatomy. The method was developed and evaluated using 8-10 repeat CT scans of 11 prostate cancer patients, prescrib...
Source: Physics in Medicine and Biology - June 6, 2018 Category: Physics Authors: Jagt TZ, Breedveld S, van Haveren R, Heijmen BJM, Hoogeman MS Tags: Phys Med Biol Source Type: research

An improved time over threshold method using bipolar signals.
In this study, we propose a novel design we developed to improve these problems occurring in the conventional TOT employing a bipolar signal and two comparators. Using a high frequency CR shaping filter, a detected signal was converted into a bipolar signal, and the positive pulse of the converted bipolar signal had a fast rising time, while the negative pulse had a linear slope. The bipolar TOT circuit was composed of a preamplifier, a CR shaping filter, and two comparators. The PET detector composed of a single LYSO coupled with 4 × 4 SiPM arrays, a bipolar TOT circuit, and an FPGA based TDC were constructed to eva...
Source: Physics in Medicine and Biology - June 6, 2018 Category: Physics Authors: Jung J, Choi Y, Kim KB, Lee S, Choe HJ Tags: Phys Med Biol Source Type: research

Carbon ions beam therapy monitoring with the INSIDE in-beam PET.
In conclusion, this work shows that the INSIDE in-beam PET scanner performance is promising towards its in-vivo test with carbon ions. PMID: 29873299 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 6, 2018 Category: Physics Authors: Pennazio F, Battistoni G, Bisogni MG, Camarlinghi N, Ferrari A, Ferrero V, Fiorina E, Morrocchi M, Sala PR, Sportelli G, Wheadon R, Cerello P Tags: Phys Med Biol Source Type: research

Energy optimization in gold nanoparticle enhanced radiation therapy.
This study quantifies the effect of varying photon beam energies on various beam arrangements, body, tumour and cellular GNP uptake geometries. Cell survival was modeled based on our previously developed GNP-Local Effect Model (LEM) with radial doses calculated using the TOPAS-nBio Monte Carlo code. Cell survival curves calculated for tumour sites with GNPs were used to calculate the relative biological effectiveness (RBE) weighted dose. In order to evaluate the plan quality, the ratio of the mean dose between the tumour and normal tissue for 50 - 250 kVp beams with GNPs was compared to the standard of care using 6 MV phot...
Source: Physics in Medicine and Biology - June 6, 2018 Category: Physics Authors: Sung W, Schuemann J Tags: Phys Med Biol Source Type: research

Corrigendum: Potential role of the glycolytic oscillator in acute hypoxia in tumors (2015 < i > Phys. Med. Biol. < /i > 60 9215).
Corrigendum: Potential role of the glycolytic oscillator in acute hypoxia in tumors (2015 Phys. Med. Biol. 60 9215). Phys Med Biol. 2018 Jun 06;: Authors: Che Fru L, Adamson EB, Campos DD, Fain SB, Jacques SL, van der Kogel AJ, Nickel KP, Song C, Kimple RJ, Kissick MW Abstract At the time of publication, our group had performed short tandem repeat (STR) testing on the SCC22B cell line and believed that had been correctly identified. As part of a recent comprehensive process to confirm the identity of cell lines in use in our lab, we repeated STR testing on all cell lines. These results were compared t...
Source: Physics in Medicine and Biology - June 6, 2018 Category: Physics Authors: Che Fru L, Adamson EB, Campos DD, Fain SB, Jacques SL, van der Kogel AJ, Nickel KP, Song C, Kimple RJ, Kissick MW Tags: Phys Med Biol Source Type: research

Sparse intervertebral fence composition for 3D cervical vertebra segmentation.
This study proposed a novel statistical model for cervical vertebra segmentation, called sparse intervertebral fence composition (SiFC), which can reconstruct the boundary between adjacent vertebrae by modeling intervertebral fences. The complex shape of the cervical spine is replaced by a simple intervertebral fence, which considerably reduces the difficulty of cervical segmentation. The final segmentation results are obtained by using a 3D active contour deformation model without shape constraint, which substantially enhances the recognition capability of the proposed method for objects with complex shapes. The proposed ...
Source: Physics in Medicine and Biology - June 5, 2018 Category: Physics Authors: Liu X, Yang J, Song S, Cong W, Jiao P, Song H, Ai D, Jiang Y, Wang Y Tags: Phys Med Biol Source Type: research

An evaluation method of clinical impact with setup, range, and radiosensitivity uncertainties in fractionated carbon-ion therapy.
Abstract In light ion therapy, the dose concentration is highly sensitive to setup and range errors. Here we propose a method for evaluating the effects of these errors by using the correlation between fractions on tumour control probability (TCP) in carbon-ion therapy. This method incorporates the concept of equivalent stochastic dose (Cranmer-Sargison and Zavgorodni 2005), which was defined as a dose that gives the mean expected survival fraction (SF) for the stochastically variable dose. The mean expected SFs were calculated while considering the correlation between fractions for setup and range errors. By usin...
Source: Physics in Medicine and Biology - June 4, 2018 Category: Physics Authors: Sakama M, Kanematsu N Tags: Phys Med Biol Source Type: research

Optimization based beam-hardening correction in CT under data integral invariant constraint.
Abstract In computed tomography (CT), the polychromatic characteristics of x-ray photons, which are emitted from a source, interact with materials and are absorbed by a detector, may lead to beam-hardening effect in signal detection and image formation, especially in situations where materials of high attenuation (e.g., the bone or metal implants) are in the x-ray beam. Usually, a beam-hardening correction (BHC) method is used to suppress the artifacts induced by bone or other objects of high attenuation, in which a calibration-oriented iterative operation is carried out to determine a set of parameters for all si...
Source: Physics in Medicine and Biology - June 4, 2018 Category: Physics Authors: Tang S, Huang K, Cheng Y, Mou X, Tang X Tags: Phys Med Biol Source Type: research

The potential of time-multiplexed steering in phased array microwave hyperthermia for head and neck cancer treatment.
Abstract Clinical studies have shown that hyperthermia sensitizes tumor cells for conventional therapies. During phased-array microwave hyperthermia, an array of antennas is used to focus the electromagnetic waves at the target region. Selective heating, while preserving the healthy tissue, is a demanding challenge and currently patient specific pre-treatment planning is used to optimize the amplitudes and phases of the waves. In addition, when needed, this single optimal heat distribution is adapted using the simulations based on the feedback from thermo-sensors and the patient. In this paper, we hypothesize that...
Source: Physics in Medicine and Biology - June 4, 2018 Category: Physics Authors: Cappiello G, Drizdal T, McGinley B, O'Halloran M, Glavin M, van Rhoon GC, Jones E, Paulides MM Tags: Phys Med Biol Source Type: research

Monte Carlo tree search -based non-coplanar trajectory design for station parameter optimized radiation therapy (SPORT).
Conclusion: AI based on MCTS is valuable to facilitate the design of beam trajectory and paves the way for future clinical use of non-coplanar treatment delivery. . PMID: 29863493 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - June 4, 2018 Category: Physics Authors: Dong P, Liu H, Xing L Tags: Phys Med Biol Source Type: research